Warming Defense No Warming
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AT: Ocean ConveyorOcean conveyor isn’t slowing down—their evidence doesn’t look to the long termWatts 10. (3/29/10. Anthony, meteorologist. “Atlantic conveyor belt—still going strong and will be the day after tomorrow” Watts Up With That. http://wattsupwiththat.com/2010/03/29/atlantic-conveyor-belt-still-going-strong-and-will-be-the-day-after-tomorrow/) The Gulf Stream does not appear to be slowing down, say US scientists who have used satellites to monitor tell-tale changes in the height of the sea. Confirming work by other scientists using different methodologies, they found dramatic short-term variability but no longer-term trend. A slow-down – dramatised in the movie The Day After Tomorrow – is projected by some models of climate change. The research is published in the journal Geophysical Research Letters. The stream is a key process in the climate of western Europe, bringing heat northwards from the tropics and keeping countries such as the UK 4-6C warmer than they would otherwise be. It forms part of a larger movement of water, the Atlantic Meridional Overturning Circulation, which is itself one component of the global thermohaline system of currents. Between 2002 and 2009, the team says, there was no trend discernible – just a lot of variability on short timescales. The satellite record going back to 1993 did suggest a small increase in flow, although the researchers cannot be sure it is significant. “The changes we’re seeing in overturning strength are probably part of a natural cycle,” said Josh Willis from Nasa’s Jet Propulsion Laboratory (JPL) in California. “The slight increase in overturning since 1993 coincides with a decades-long natural pattern of Atlantic heating and cooling.” Short measures The first observations suggesting the circulation was slowing down emerged in 2005, in research from the UK’s National Oceanography Centre (NOC). Using an array of detectors across the Atlantic and comparing its readings against historical records, scientists suggested the volume of cold water returning southwards could have fallen by as much as 30% in half a century – a significant decline. The surface water sinks in the Arctic and flows back southwards at the bottom of the ocean, driving the circulation. However, later observations by the same team showed that the strength of the flow varied hugely on short timescales – from one season to the next, or even shorter. But they have not found any clear trend since 2004. Gulf stream shutdown unlikely, and there is no impact even if it does The Guardian 11. (3/29/11. “Will the Gulf Stream slow down, freezing the UK and northern Europe?” http://www.guardian.co.uk/environment/2011/mar/29/climate-gulf-stream-atlantic-drift-thermohaline) The Gulf Stream and North Atlantic Drift – which are part of the Atlantic thermohaline circulation – bring warm water, and with it warm air, from the tropical Atlantic to northern Europe. This helps keep the UK several degrees warmer than it would otherwise be. Although this system is unlikely to pack up entirely, the IPCC deems a slowdown of it "very likely" over the next century. The reason is that increasing rainfall and snow-melt across the Arctic and nearby land areas could send more freshwater into the north Atlantic, pinching off part of the warm current. The best guess from the most sophisticated computer models is that the circulation might slow by 10% to 50% over the next century, if greenhouse gas emissions continue unabated. If this happens, the expected climate warming might be nearly erased across the United Kingdom and diminished across many other parts of Europe. However, summers could still be warmer and more drought-prone across the UK and Europe than they are now. In any case, the impacts would be much smaller – and would take much longer to play out – than the scenario dramatised in the film The Day After Tomorrow. Although evidence shows that the thermohaline circulation has ground to a halt more than once in climate history, it's believed that this process takes at least a few years to play out, and sometimes many decades, rather than the few days portrayed in the film. AT: Non-Anthro WarmingOnly human activity solves warmingBBC Focus Magazine, ‘11 (2/28/11, “Is global warming preventing the next ice age?” http://sciencefocus.com/qa/global-warming-preventing-next-ice-age) Ice ages are controlled by cyclic changes in the Earth's orbit and orientation, and calculations suggest another one should have begun several thousand years ago. In 2005, a team led by Professor William Ruddiman of the University of Virginia suggested that man-made global warming might be holding back the next big freeze. They argued that ancient agricultural practices, deforestation and biomass-burning may have boosted levels of carbon dioxide and methane, and thus cancelled out the cooling produced by the astronomical cycles. Evidence for the idea has continued to accumulate. Last December, an international team of climate experts presented an analysis of air trapped in ice cores, which reveals the composition of the atmosphere over thousands of years. The results show that both carbon dioxide and methane began increasing around 5000 to 8000 years ago. This is in line with the historical origins of large-scale agriculture in Asia and extensive deforestation in Europe - and thus adds weight to the idea that human activity may indeed be holding off the next ice age. AT: Sunspots OutweighCO2 emissions solve sunspot coolingBognor, 7/4 [Howard, Owen Sound Sun Times, “Global warming may help fend off another ice age,” http://www.owensoundsuntimes.com/ArticleDisplay.aspx?e=3198084, DS] But before we all go out and paint our roofs white it is important to consider some real concerns that the planet may be heading not for global warming, but for another mini-ice age. In June NASA warned that the much delayed solar Cycle 24 may end abruptly and that Cycle 25 may not occur at all. Reduced sunspot activity may be associated with reduced solar luminosity which, in turn, would cool the Earth's ionosphere and the upper stratosphere. That is, disappearing sunspots may cause the Earth's temperature to decrease. The last time this occurred was the period known as the Maunder minimum from 1645 to 1715, which coincided with a mini-ice age across Europe. Prior to that was the Sporer minimum (about 1500) and the Wolf minimum (about 1300). Why they occur at roughly 200 year intervals is unknown, but it is known that the Earth's mean temperature decreased at these times. Also consider that last year's Icelandic volcano spewed an amount of ash into the Earth's stratosphere that was comparable to that believed responsible for the demise of the dinosaurs (and 80% of all life forms on Earth) caused by the impact of a comet or asteroid 65 million years ago. This ash was spread around the Earth by the jet streams and reduced the surface temperature by several degrees. While it is true that the ice caps are melting and the glaciers receding, these observations are due to secular warming as a consequence of the end of the last ice age. About 9,000 years ago our region was covered by a two-mile thick sheet of ice that was one of the southern lobes of the great ice sheet that covered all of Canada and much of the U.S. The periodic advances and retreats of these ice sheets are controlled by well-understood variations in the Earth's orbital eccentricity about the Sun and variations in the Earth's tilt axis and wobble. Currently we are in the end-stages of the retreat of the last ice sheets. It may very well turn out that any man-made contributions to global warming may be just what Earth needs to ameliorate natural processes that seem to be conspiring to force another mini-ice age on us. Directory: files files -> Answer True False 2 points Question 2 files -> Integer programming and game theory files -> 4 Integer Programming files -> Bpa vehicle Window Repair Scenario #1 task: Procure vehicle window relacement. Objective files -> Pop Warner History files -> North Carolina Inclusion Initiative Mapping Where Children with ieps are Being Served Purpose files -> Fall 2013 Spring 2014 Program Data: Standard 1 Exhibit 4d files -> Hanban – asia society confucius classrooms network 2010 request for proposal files -> Northern England’s set-jetting locations Download 202.14 Kb. Share with your friends:
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